security: code cleanup and doxygen improvements in tpm::BackEndOsx

Change-Id: I6d6d77ab315a10c280e7643d4cec5269ed10fe5e
diff --git a/src/util/cf-string-osx.cpp b/src/util/cf-string-osx.cpp
new file mode 100644
index 0000000..a0d3814
--- /dev/null
+++ b/src/util/cf-string-osx.cpp
@@ -0,0 +1,71 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2018 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "cf-string-osx.hpp"
+
+namespace ndn {
+namespace util {
+namespace cfstring {
+
+CFReleaser<CFStringRef>
+fromBuffer(const uint8_t* buf, size_t buflen)
+{
+  CFStringRef cfStr = CFStringCreateWithBytes(kCFAllocatorDefault, buf, buflen, kCFStringEncodingUTF8, false);
+  if (cfStr == nullptr) {
+    BOOST_THROW_EXCEPTION(std::runtime_error("Failed to create CFString from buffer"));
+  }
+  return cfStr;
+}
+
+CFReleaser<CFStringRef>
+fromStdString(const std::string& str)
+{
+  CFStringRef cfStr = CFStringCreateWithCString(kCFAllocatorDefault, str.data(), kCFStringEncodingUTF8);
+  if (cfStr == nullptr) {
+    BOOST_THROW_EXCEPTION(std::runtime_error("Failed to create CFString from std::string"));
+  }
+  return cfStr;
+}
+
+std::string
+toStdString(CFStringRef cfStr)
+{
+  const char* cStr = CFStringGetCStringPtr(cfStr, kCFStringEncodingUTF8);
+  if (cStr != nullptr) {
+    // fast path
+    return cStr;
+  }
+
+  // reserve space for the string + null terminator
+  std::string str(CFStringGetLength(cfStr) + 1, '\0');
+  // copy the CFString into the std::string buffer
+  if (!CFStringGetCString(cfStr, &str.front(), str.size(), kCFStringEncodingUTF8)) {
+    BOOST_THROW_EXCEPTION(std::runtime_error("CFString to std::string conversion failed"));
+  }
+  // drop the null terminator, std::string doesn't need it
+  str.pop_back();
+
+  return str;
+}
+
+} // namespace cfstring
+} // namespace util
+} // namespace ndn
diff --git a/src/util/cf-string-osx.hpp b/src/util/cf-string-osx.hpp
new file mode 100644
index 0000000..c44fed4
--- /dev/null
+++ b/src/util/cf-string-osx.hpp
@@ -0,0 +1,68 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2018 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_UTIL_CF_STRING_OSX_HPP
+#define NDN_UTIL_CF_STRING_OSX_HPP
+
+#include "../common.hpp"
+
+#ifndef NDN_CXX_HAVE_OSX_FRAMEWORKS
+#error "This file should not be included ..."
+#endif
+
+#include "cf-releaser-osx.hpp"
+
+/**
+ * @file
+ *
+ * This file contains utilities to deal with Apple Core Foundation's CFString and related types.
+ */
+
+namespace ndn {
+namespace util {
+namespace cfstring {
+
+/**
+ * @brief Create a CFString by copying bytes from a raw buffer
+ * @throw std::runtime_error creation failed
+ */
+CFReleaser<CFStringRef>
+fromBuffer(const uint8_t* buf, size_t buflen);
+
+/**
+ * @brief Create a CFString by copying characters from a std::string
+ * @throw std::runtime_error creation failed
+ */
+CFReleaser<CFStringRef>
+fromStdString(const std::string& str);
+
+/**
+ * @brief Convert a CFString to a std::string
+ * @throw std::runtime_error conversion failed
+ */
+std::string
+toStdString(CFStringRef cfStr);
+
+} // namespace cfstring
+} // namespace util
+} // namespace ndn
+
+#endif // NDN_UTIL_CF_STRING_OSX_HPP